Partially bonded type c core



Sept. 10, 1957 w, KUHN PARTIALLY BONDED TYPE "C" CORE Filed March 25, 1955 A ,fll

' INVENTOR E und .Kuhn.

United States Patent Ofifice 3 Claims. (Cl. 336-210) Pa., assignor to Westinghouse East Pittsburgh, Pa., a corpora- The invention relates generally to cores for inductive apparatus and, more particularly, to cores Wound from oriented silicon steel.

It has been found that in the making of wound cores, particularly of the type which are cut into sections and fitted around preformed coils, that some difiiculty has been experienced in fitting the matching faces of the ends of the sections with the result that joints having losses which meet requirements for low magnetizing current are not quite effected.

In some instances, the cores due to processing become slightly distorted from their original set, and V-shaped gaps may result.

The object of the invention is to provide in the wound core having matching faces sufficient flexibility in the core sections to enable the accurate fitting of the faces to one another to provide a low loss butt joint with a low noise level.

Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter.

The invention, accordingly, comprises the features of construction, combination of elements, and arrangement of parts, which will be exemplified in the construction hereinafter set forth, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description, taken in connection with the accompanying drawing, in which:

Figure 1 is a view in side elevation of the sections of a wound core illustrating the prior art;

Fig. 2 is a view in side elevation of the sections of a wound core embodying the features of the invention;

Fig. 3 is a view in side elevation of the sections of a wound core showing in a somewhat exaggerated manner how the core sections prepared by some of the processes of the prior art fit together after they have been processed; and

Fig. 4 is a view in side elevation showing the section of a wound core after they have been processed and fitted together in accordance with the teachings of the invention, the shape of the core being slightly exaggerated to illustrate the advantages of the structure.

Referring now to the drawing, and Fig. 1 in particular, the core shown generally at comprises two sections 11 and 12, each of which have two legs and are generally described in the trade as C-core sections. The C-core sections as shown in the drawings may be more accurately described as being U-shaped each being made of a plurality of U-shaped laminations. In manufacturing operations, after the C-core sections 11 and 12 have been properly processed, they are fitted around preformed coils with the matching faces fitted closely together with the objective of providing low loss joints.

It has been found that in the processing, the C-core sections 11 and 12 may become slightly distorted with the result that when they are fitted together after processing they will present gaps, such as shown at 13 in Fig. 2.

2,806,212 Patented Sept. 10, 1957 When this results, an effort is made to draw the matching faces of the core sections together, so as to contact throughout the full surface area. However, since the usual practice is to impregnate the laminations of the core sections with a suitable bonding material, the C-core sections 11 and 12 have become quite rigid, and it is very difficult to bring them into complete contact throughout the whole matching face area.

Of course, it is to be understood that this is not always the case in the manufacturing of C-core sections, and that cores which are manufactured are usually carefully fitted so that they present low loss joints. However, many cores have to be scrapped in the process of manufacture because they do not fit as accurately as required by manufacturers.

Referring now to Fig. 2, in accordance with the teaching of this invention, in the manufacture of the core sections 11 and 12, the section 12 is completely impregnated with bonding material, but the section 11 is not. As shown, only a predetermined length 14 of the ends of the section 11 is impregnated with a suitable bonding material.

The laminations 15 which are usually wound from oriented silicon steel are free to move relative to one another between the bonded end sections 14. This gives flexibility to the section 11. Therefore, in fitting the core sections 11 and 12 around a preformed coil, the section can be slightly distorted from the set it has taken after the processing has been completed to enable the bringing of the matching faces of the core sections into complete engagement to give low losses and low noise level.

By reference to Fig. 4, it will be observed that the section ll of the core is somewhat distorted and the matching faces meet throughout their complete area and no gap appears, as shown in Fig. 3. Of course, the dis tortion which occurs at 16 in the legs of the core is somewhat distorted, in order to show what takes place in the flexible portion of the core section to enable the drawing of the matching faces into contact throughout the whole area.

Further, the core sections 11 and 12 in Fig. 4 are not illustrated as applied to a coil in order to show how the matching faces fit together. However, it will be appreciated that the core sections 11 and 12 could be drawn together by the banding strap 17 as readily if they were fitted around preformed coils.

It is usual practice in manufacturing cores of this type to use a tension device for drawing the banding strap 17 to the proper tightness and then locking it by means of the clamp 18. This method of banding C-core sections is well known in the art, and the applying of the proper tension may readily be accomplished by known methods. Therefore, the device for performing this operation has not been illustrated.

It is also pointed out that suitable bonding materials for bonding the laminations to one another is well known in the art and have not been described.

Since certain changes may be made in the above construction and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In a wound core structure, in combination, a plurality of substantially U-shaped core sections presenting legs of predetermined size and shape and having matching end faces, each core section comprising a plurality of laminations, bonding material applied to one of the core sections bonding the laminations to one another forming a substantially rigid unit, bonding material applied to the end portions of the legs of the other core section for a substantial distance below the matching end faces, bonding the laminations to one another, the .portions of the laminations between the bonded end portions being free to move to give the core section flexiblity to enable the drawing of the matching faces of the substantially rigid core section and the core section having flexibility into substantially complete contact with one another to provide a low loss joint withlow noise level;

2. In a wound core structure, in combination, a plurality of U-shaped core sections having matching faces capable of being fitted together to make substantially complete contact throughout :their meeting areas, each of the core sections comprising a plurality of U-shaped laminations in stacked relationship presenting legs of predetermined size and shape, bonding material applied to zone of the .core sections to completely bond'the laminations to one another making a substantially rigid U-shaped core section, bonding material applied to the ends of the legs of the other core section for a substantial distance below the matching end faces, bonding the laminations to one another, the portions of the laminations between the bonded leg sections being free to move relative to one another to give the core flexibility whereby when the matching faces of the substantially rigid core section are applied to the matching faces of the core section having flexibility, the matching faces may be drawn into substantially complete contact with one another to provide a low loss joint with low noise level.

a l -'a,soe,212

3. In a wound core structure, in combination, a plurality of U-shaped core sections presenting .legs of predetermined size and shape and having matching end faces at the ends of the legs, each U-shaped core section comprising a plurality of U-shaped laminations, bonding material applied to the laminations of one of the core sections bonding the laminations to one another forming a substantially rigid unit, bonding material applied to a predetermined length of the ends of the legs of the other core section to bond the laminations to one another adjacent the matching end faces, the laminations of the core section between the bonded end portions being free topermit relative movement to give the core section flexibility, whereby when the substantially rigid core section and a core section having flexibility are assembled with their matching faces aligned, the matching faces may be brought into complete contact by the applying of pressure and means for applying pressure to efi'ect the bringing of the matching faces of the core section's into substantially complete contact with one another to make a low loss joint with low noise level.

References Cited in the file of this patent UNITED STATES PATENTS 2,318,095 Putnam May 4, 1943 2,478,029 Vienneau Aug. 2, 1949 2,488,391 Ford et al Nov. 15, 1949 2,523,071 Somerville Sept. 19, 1950 

